1. Field of Invention
The present invention relates to a TV (television) demodulator capable of calibrating its output and a calibration method thereof; particularly, it relates to such a TV demodulator capable of generating an accurate output signal under a situation where a resistance of a TV transmission wire is unknown, and a calibration method thereof.
2. Description of Related Art
In a conventional TV demodulator, the output signal is often affected by the resistance of the back-end circuit connected to the output of the TV demodulator. In order to generate an accurate output signal, the prior art adopts external add-on resistors, to match with a resistance of a TV transmission wire which is connected to the output of the TV demodulator.
Nevertheless, because the resistance of the TV transmission wire is unknown, the add-on resistors may not always match with the resistance of the TV transmission wire, thus failing to generate the desired accurate output signal. As a consequence, an issue such as that the color level cannot be full level, or other problems, may arise.
The following patents disclose contents which are related to the present invention: U.S. Pat. No. 8,767,129, U.S. Pat. No. 7,352,238 and U.S. Pat. No. 4,544,911.
In view of the above, to overcome the drawbacks in the prior art, the present invention proposes a TV demodulator capable of calibrating its output, and a calibration method thereof. The TV demodulator is capable of generating an accurate output signal under a situation where a value of the resistance of the TV transmission wire is unknown. Besides, the present invention provides two operation modes: a high quality mode and a low power consumption mode, which increases the flexibility in application.